Hmm, I did some shooting up to 30 yards today and got one hell of a surprise when I decided to see what the trajectory looks like.
The rifle is sighted for roughly 25 Yards.
At 10 yards the grouping is 2" low
At 15 yards the grouping is about 3/4 - 1" low
At 20 yards the grouping is about 1/2" low
At 25 yards the grouping is dead on
At 30 Yards the grouping is 1/2 - 3/4" High
Power/ speed is not an issue, the pellets punch straight through a 16mm Melamine board at any of the above distances, further to this the groupings stay tight and any deviation from the pattern is purely shooter error as I do not have an X-Bag or front rest, only a scatter cushion and a brick with a sock over it, perched on a wobbly table.
Specs of the rifle, Pellets and telescope:
Rifle: Webley Raider 10, Stock standard but not limited to 12FP energy.
Scope: Nikko Stirling Night-Eater 3.5 - 10 X42 mounted on Gamo rings.
Pellets: JSB Match Exact Diabolo 13.73 grain